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  Home > JCE Print > Journal of Chemical Education > Issues > 2008  > March  >
In the Laboratory
Supramolecular Inclusion in Cyclodextrins: A Pictorial Spectroscopic Demonstration
Basudeb Haldar, Arabinda Mallick, and Nitin Chattopadhyay
Department of Chemistry, Jadavpur University, Calcutta 700 032, India
Cover
March 2008
Vol. 85 No. 3
p. 429

Abstract
A spectroscopic experiment is presented that reveals that the hydrophobically end-modified water-soluble polymeric fluorophore, pyrene end-capped poly(ethylene oxide) (PYPY), interacts differently with α, β, and γ-cyclodextrins (CD) to form supramolecular inclusion complexes. The emission spectrum of PYPY in aqueous solution shows characteristic dual emission; the pyrene monomer emission and the excimer emission. α-CD does not affect the absorption and emission spectra of the fluorophore. In β-CD solution, the excimer emission yield decreases with a concomitant enhancement of the monomer emission while the fluorescence spectral observation in γ-CD is qualitatively opposite. The differences in the photophysical behavior of the fluorophore in different CD environments establish different modes of encapsulation of PYPY in CDs with different cavity dimensions. The different modes of encapsulation are explained from the relative dimensions of the pyrene units and the various CD cavities. The cavity of α-CD is too small to form an inclusion complex with the fluorophore. β-CD cavity has the proper dimension to encapsulate one pyrene unit of the polymer and γ-CD cavity is large enough to include both the fluorophore end-groups in stacked orientation.
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Synthetic details; Instructor notes
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Citation
Haldar, Basudeb; Mallick, Arabinda; Chattopadhyay, Nitin. J. Chem. Educ. 2008, 85, 429.
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Keywords
Aqueous Solution Chemistry; Aromatic Compounds; Fluorescence Spectroscopy; Graduate Education / Research; Hands-On Learning / Manipulatives; Inquiry-Based / Discovery Learning; Laboratory Instruction; Noncovalent Interactions; Photochemistry; Physical Chemistry; Physical Properties; Spectroscopy; Upper-Division Undergraduate; UV-Vis Spectroscopy
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History
Created:
Last Updated:
2/4/2008
2/8/2008
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Experiments, laboratory exercises, lecture demonstrations, and other descriptions of the use of chemicals, apparatus, instruments, computers, and computer interfaces are presented in the Journal of Chemical Education as illustrative of new or improved ideas or concepts in chemistry instruction and are directed at qualified teachers. Although every effort is made to assure and encourage safe practices and safe use of chemicals, the Journal of Chemical Education cannot assume responsibility for uses made of its published materials. Many chemicals are hazardous. Precautions for the safe use of hazardous chemicals and directions for their proper disposal are described in the Material Safety Data Sheets and on the labels. We strongly urge all those planning to use materials from our pages to make choices and to develop procedures for laboratory and classroom safety in accordance with local needs and situations.
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